import (
	"text/scanner"

	"cmd/internal/src"
)

// A Stack is a stack of TokenReaders. As the top TokenReader hits EOF,
// it resumes reading the next one down.
type Stack struct {
	tr []TokenReader
}

// Push adds tr to the top (end) of the input stack. (Popping happens automatically.)
func (s *Stack) Push(tr TokenReader) {
	s.tr = append(s.tr, tr)
}

func (s *Stack) Next() ScanToken {
	tos := s.tr[len(s.tr)-1]

  public final void addTearDown(TearDown tearDown) {
    synchronized (stack) {
      stack.addFirst(checkNotNull(tearDown));
    }
  }

  /** Causes teardown to execute. */
  public final void runTearDown() {
    List<Throwable> exceptions = new ArrayList<>();
    List<TearDown> stackCopy;
    synchronized (stack) {
      stackCopy = Lists.newArrayList(stack);
      stack.clear();
    }
    for (TearDown tearDown : stackCopy) {

	"cmd/asm/internal/flags"
	"cmd/internal/objabi"
	"cmd/internal/src"
)

// Input is the main input: a stack of readers and some macro definitions.
// It also handles #include processing (by pushing onto the input stack)
// and parses and instantiates macro definitions.
type Input struct {
	Stack
	includes        []string
	beginningOfLine bool
	ifdefStack      []bool
	macros          map[string]*Macro

	"signal.signal_recv",
	"sigterm.handler",
	"runtime_mcall",
	"goroutine in C code",
}

// Identify whether the stack trace entry is part of ignoredStackFn .
func isIgnoredStackFn(stack string) (ok bool) {
	ok = true
	for _, stackFn := range ignoredStackFns {
		if !strings.Contains(stack, stackFn) {
			ok = false
			continue
		}
		break
	}
	return ok
}

    public void enter() {
        LinkedList<ScopeState> stack = values.get();
        if (stack == null) {
            stack = new LinkedList<>();
            values.set(stack);
        }
        stack.addFirst(new ScopeState());
    }

    private ScopeState getScopeState() {
        LinkedList<ScopeState> stack = values.get();
        if (stack == null || stack.isEmpty()) {
            throw new IllegalStateException();

    }

    return builder.buildOrThrow();
  }

  /**
   * Parses a trie node and returns the number of characters consumed.
   *
   * @param stack The prefixes that precede the characters represented by this node. Each entry of
   *     the stack is in reverse order.
   * @param encoded The serialized trie.
   * @param start An index in the encoded serialized trie to begin reading characters from.

  public void testSingleTearDown() throws Exception {
    final TearDownStack stack = buildTearDownStack();

    final SimpleTearDown tearDown = new SimpleTearDown();
    stack.addTearDown(tearDown);

    assertEquals(false, tearDown.ran);

    stack.runTearDown();

    assertEquals("tearDown should have run", true, tearDown.ran);
  }

  public void testSingleTearDown() throws Exception {
    final TearDownStack stack = buildTearDownStack();

    final SimpleTearDown tearDown = new SimpleTearDown();
    stack.addTearDown(tearDown);

    assertEquals(false, tearDown.ran);

    stack.runTearDown();

    assertEquals("tearDown should have run", true, tearDown.ran);
  }

class DocBookBuilder {
    final LinkedList<Element> stack = new LinkedList<Element>();
    final Document document;

    DocBookBuilder(Document document) {
        this.document = document;
        stack.addFirst(document.createElement("root"));
    }

    List<Element> getElements() {
        List<Element> elements = new ArrayList<Element>();

    private final Deque<Iterator<T>> stack;

    PreOrderIterator(T root) {
      this.stack = new ArrayDeque<>();
      stack.addLast(Iterators.singletonIterator(checkNotNull(root)));
    }

    @Override
    public boolean hasNext() {
      return !stack.isEmpty();
    }

    @Override
    public T next() {
      Iterator<T> itr = stack.getLast(); // throws NSEE if empty